Bracon wasps for ecological pest control–a laboratory experiment

Abstract

Biological control of pest insects by natural enemies may be an effective, cheap and environmentally friendly alternative to synthetic pesticides. The cosmopolitan parasitoid wasp species Bracon brevicornis Wesmael and B. hebetor Say (Hymenoptera: Braconidae) use lepidopteran species as hosts, including insect pests like Ephestia kuehniella or Ostrinia nubilalis. Here, we compare the reproductive success of both Bracon species on E. kuehniella in a laboratory experiment. We asked (1) how the reproductive success on a single host larva changes with temperature, (2) how it changes with temperature when more host larvae are present and (3) how temperature and availability of host larvae influence the efficacy of Bracon species as biological control agents. In general, differences between B. brevicornis and B. hebetor have been small. For rearing both Bracon species in the laboratory on one host larva, a temperature between 20–27 °C seems appropriate to obtain the highest number of offspring with a female-biased sex ratio. Rearing the braconid wasps on more than one host larva revealed a higher number of total offspring but less offspring per host larva on average. Again, highest numbers of offspring hatched at 27 °C and the sex ratio was independent from temperature. Although no parasitoids hatched at 12 °C and only few at 36 °C, host larvae were still paralyzed. The efficacy of B. brevicornis was higher than 80% at all numbers of host larvae presented at all temperatures while the efficacy of B. hebetor was less than 80% at 12 °C and 27 °C at low numbers of host larvae presented. In conclusion, practitioners can use either B. brevicornis or B. hebetor at low and high temperatures and at varying host densities to achieve high pest control efficacy.

Impact of Some Gamma-Irradiated Hosts on Bracon Brevicornis Wesmael Parasitism and Production

“…On the other hand, Hasan et al (2019) evaluated possible improvements to the mass rearing of the larval parasitoid Habrobracon hebetor on irradiated G. mellonella and Plodia interpunctella at the dose of 150Gy proved useful for enhancing parasitism and adult emergence of H. hebetor, with significantly higher parasitism recorded at 150 and Female parasitoids favored irradiated larvae and parasitized a substantially higher number of larvae than nonirradiated larvae. Lettmann et al (2021) found that using a total number of ten host larvae to enhance the overall number of progeny and one female wasp is recommended to keep the number of hatched parasitoids per host at a high level to obtain a high level of pest management efficiency; practitioners can utilize either B. brevicornis or B. hebetor at low and high temperatures, as well as with varied host densities.…”

“…The ecto-parasitoid Braconidae wasps is one of the parasitoid families' most diverse with numerous parasites (LaSalle & Gauld 1993). Bracon brevicornis Wesmael (Hymenoptera: Braconidae) is a gregarious insect that attacks many pests of Lepidoptera species as a larval ectoparasitoid (Brower et al 1996).…”

Effect of Adult Nutrition at Different Concentrations on Reproduction and Longevity of <i>Bracon brevicornis</i>, Larval Parasitoid of Coconut Black-Headed Caterpillar

“…Parasitoid nutrition is important in evaluating its reproductive performance and life span. Several studies mentioned that diluted honey [10] or sugary water [12] in general, without specifying certain concentrations, could be used when rearing B. brevicornis on S. frugiperda or E. kuehniella. However, Wei et al reported that honey-feeding and host hemolymph-feeding parasitoid shows similar effect on reproduction and longevity [13].…”